Precision Power PC1400 - Manual (Page 17)

15
C r o s s o v e r
PC-1400
Your new Monoblock amplifier has a variable 20-5kHz 12dB/Octave HP/
LP crossover. When you select the LP feature on this amplifier you have
made the output RCA's HP, and vice versa when you select HP for the
speaker output.
PC-1800
The PC-1400 has a variable fourth-order Linkwitz-Riley type, 24dB per
octave LP crossover built in to provide system flexibility without the added
expense and installation of an outboard crossover. The speaker outputs of
the amplifier are all pass or LP according to the LP ON/OFF switch on the
amplifier's front endplate. You would choose LP (switch in) to use this amp
for subwoofers, or choose all pass (switch out) to use this amp for full
range speakers. Selection of low pass lets you vary the crossover point
from 50Hz to 300Hz using the detented LP FREQ. control, 50Hz being
fully counterclockwise. (see frequency detent charts on pg.16 )
Subsonic Filter
You will also find the SUBSONIC ON/OFF switch on the front endplate of
your PC-1800. This is a 24dB per octave HP crossover used to clean up
the sound of your subwoofers, and is especially useful with ported or
bandpass sub enclosures with steeper rolloffs at low frequencies. With
the Subsonic filter switch in, you can vary the HP frequency from 5Hz
to 50Hz using the detented SUBSONIC FREQ. control, 5Hz being fully
counterclockwise. Refer to the Frequency Chart on page 13 to set your
frequency or adjust the filter to the lowest frequency and turn the control
clockwise as the music plays. You will notice increased detail to a point
and then you will notice a decrease in bass. Turn back to the detent
frequency just before you started losing bass.
A d j u s t i n g T h e A m p l i f i e r I n p u t G a i n
1. Adjust all amplifier input gain controls to just above minimum
sensitivity (fully counterclockwise).
2. Using the cleanest source (CD), with music playing turn up
the head unit until you can hear distortion. Now turn it down a
bit until you cannot hear the distortion.
3. Increase the Amplifier gain (clockwise) until the onset of
audible distortion. Then decrease the gain to the point just
before the distortion starts. This setting minimizes background
noise and prevents overload.
4. Repeat step 3 for any remaining amplifiers in the system.
CROSSOVER, SUBSONIC and GAIN
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